Oren Peli ('Paranormal Activity')

Breaking the $100 million barrier in the US a few weeks ago, Oren Peli's demonic horror Paranormal Activity, which finds Katie Featherston and Micah Sloat's young couple terrorised by an evil spirit, has morphed from a much-discussed $15,000 chiller into a bona fide blockbuster. DS caught up with Peli to find out about the film's incredible success, spooking Steven Spielberg, and why he's still living in the house he filmed the movie in.

What were your initial hopes when you started making the film? Did you ever expect it to go this far?"I was hoping that after seeing the success of movies like The Blair Witch Project and Open Water, if the movie turned out well maybe it would have some future in theatres. I didn't really know until I started playing the movie in test screenings and saw the reaction, then I started thinking, 'Maybe we really could have a future in theatrical distribution'."

Why do you think it had such a big effect on audiences?"A lot of people who respond to the movie find it genuinely really scary. From what we're hearing from people it's the first movie that's really scared them in a long time. It could be because of the realism or the subject matter. What happens at night when you're asleep? The primal fear that everyone shares in common."

Were there any times when you thought things wouldn't work out for the film?"At the very beginning things were moving along fairly quickly. When DreamWorks and Paramount were splitting up, for a year things were in limbo and we didn't really know what was going to happen."

What changed in the movie from that time until now and when did the input from Steven Spielberg come?"At the very last moment before Paramount released the film we had a last round of edit changes, last polish and audio clean-up. The Spielberg ending (Peli filmed a new ending at the suggestion of the director) happened while the movie was still with DreamWorks."

What's the real version of the Spielberg story?"The real version is that after we did the test screening for DreamWorks... originally they wanted to remake the movie. We did a screening and immediately they said, 'Forget about the remake, let's release the original movie'. They gave the DVD to Spielberg to give his authorisation because he owns the studio and the next day I heard that he started watching the movie and got so unnerved by it, he turned it off halfway and finished watching it during daylight. The next day he tried to get back to his bedroom and somehow it was locked from the inside. There was no other way to get in and a locksmith couldn't open it. He cut through the door with a saw and sent the movie back - he didn't want the DVD in his house."

Did you play tricks on Micah and Katie to get a more genuine reaction?"A few times. There were some scenes where they didn't know what was supposed to happen. We said 'goodnight' and then did something to surprise them. The first bang in the house, when the chandelier gets broken, they didn't know that was going to happen. Later on we [realized] they were so talented and so good that we didn't really need to do it. [There was no script], just an outline I kept to myself - they didn't know how the story was going to go and what was going to happen. All the dialog was improvised on the fly."

A lot of important moments happen off camera. Do you think that helps to heighten the fear?"If you hear a noise you don't know where it comes from, it could have come from inside the room, down the hallway or downstairs. You know something is going on but you can't tell exactly what it is. To me that can be a lot more unnerving than seeing something right in front of you happening. In many cases your imagination is much more effective than what can be shown. It primes you to know something is about to happen - the anticipation and anxiety is worse than what ends up happening."

There's a lot of silence in the film that's quite terrifying, such as when Katie is possessed and standing up for hours at the end of the bed. Where did that idea come from?"I'm really proud that scene works well because I thought it would be very cool to make the point that you can have something very simple happening and it gets a huge reaction from the audience. People are gasping and really unnerved by it. I'm very pleased that something subtle like that can get a great reaction instead of gore and blood and guts. That's actually one of my favorite scenes in the movie."

You're still living in the house where you shot the movie. Are you worried it'll become a Hollywood tourist attraction?"Yes. We've had a few people drive by and stuff. We haven't had any problems."

Do you think you've driven the final nail into the torture porn genre?"I have no idea. I think people still enjoy those kind of movies. If they're still making those movies, people are more than welcome to see them."